This invention relates to a method of purifying and treating waste water of various types, primarily that used on oil well rigs and generally in the operation of drilling oil and gas wells.
In order to meet state water quality standards in treating waste water, several specific parameters must be met:
pH: 6.0-9.0; PA1 Chlorides(Mg/L): 1000 or less; PA1 Color (units): 5000; PA1 Chemical Oxygen demand (COD) (Mg/L): 200 or less; PA1 Total Suspended Solids(Mg/L): 50 or less; PA1 Total Dissolved Solids(Mg/L): 3000 or less; PA1 Oil and Grease(Mg/L): 15 or less.
Waste water meeting these parameters may be disposed of without polluting or contaminating the environment, or of course, may be recycled for use on the drilling rig. It has been found that the introduction of flocculents such as aluminum sulfate (Alum), MFI, Lime, 5C, and the modern technology polymers to the waste water will form flocculent precipitate which coagulates fine solid impurities therein and permits them to settle to the bottom of the tank or pit while the clean, clear water is skimmed from the top or permitted to overflow into a subsequent sedimentation tank or pit.
Patents considered pertinent to the present invention include Newman, U.S. Pat. No. 1,418,013, disclosing an improvement in water purification by treating same with an alkaline bleaching agent and an coagulant; Langelier, U.S. Pat. No. 1,465,173, disclosing a water purification method involving treatment using a minimum dosage of coagulant in combination with an acid to yield ionic hydrogen and improved coagulation; Mallory, U.S. Pat. No. 2,138,349, disclosing a method and apparatus for aerating sewage using a series of internal rotating diffusing baffels; Riddick, U.S. Pat. No. 3,075,645, disclosing a water treatment system, whereby coagulant is added to the water, the mixture is aerated and then passed through a flocculation basin, then filtered; Horiguchi et al, U.S. Pat. No. 3,547,816, disclosing an aeration and filtering water purification system; Edwards, U.S. Pat. No. 3,772,188, disclosing a waste water treatment system using pressurized oxygen injection; Pradt, U.S. Pat. No. 3,876,536, disclosing a high temperature and high pressure wet air oxidation process for treating waste water; and Reimann, U.S. Pat. No. 4,029,574, disclosing a process for aerating organically contaminated sewage with oxygen.